Thurstone began his studies as an electrical engineer, developing
several motion picture innovations that attracted the attention of, and
led to an offer of employment with Thomas Edison in 1912. However,
Thurstone was more interested in studying the 'learning function', and
continued his academic studies at the University of Chicago. He later
stated that G. H. Mead's lectures on social psychology were the greatest
influence on his development in psychology.

In Thurstone's early work in psychology, he rejected the popular
stimulus-oriented psychology in favor of a person-centered approach. He
distinguished between the focus of experimental or "normal"
psychology and abnormal or psychoanalytic psychology. Thurstone believed
that experimental psychology treated the normal person as little more than
a responding machine. He advocated turning the focus of psychology from
stimuli to the "satisfaction" the normal person is trying to
attain and the way he or she attempts to attain them. Thurstone believed
that an understanding and analysis of intelligence must begin with people
and their attempts to reach their goals. Instinctual responses and lower
levels of intelligence are characterized by the tendency to act on
impulses without reflection. Higher levels of intelligence provide greater
protection and increase the likelihood that individuals will eventually
reach their goals by deflecting less than optimal impulses at earlier
stages in the process of attempting to reach a goal. He saw intelligence
is an inhibitory process:

The ability to inhibit instinctive responses while those responses
are still in a loosely organized form and to use abstraction to
redefine the instinctive behavior in light of imagined consequences.

Thurstone factor-analyzed intelligence tests and tests of perception.
In the area of intelligence, his theory was that intelligence is made up
of several primary mental abilities rather than a general and several
specific factors. He was among the first to propose and demonstrate
that there are numerous ways in which a person can be intelligent.
Thurstone's Multiple-factors theory identified these seven primary mental
abilities:

Verbal Comprehension

Word Fluency

Number Facility

Spatial Visualization

Associative Memory

Perceptual Speed

Reasoning

Thurstone's multiple factors theory has been used to construct
intelligence tests that yield a profile of the individual's performance on
each of the ability tests, rather than general intelligence tests that
yield a single score (e.g. IQ).